In wireless communications systems, pulse-shaping of digital data is usually needed to meet system spectral emission requirements. Instead of using conventional filters to shape pulses, however, a look-up table is often used to approximate the filtering operation and reduce the cost and complexity of the pulse-shaping operation. The digital data is translated into digital words, and a look-up table maps each digital word to an output waveform segment stored in the table. Due to the look-up table, the first output waveform segment in a pulse-shaping digital data output waveform sequence may have an abrupt transition from a zero value to a positive or negative value. Likewise, the last output waveform segment in an output waveform sequence may have an abrupt transition from a positive or negative value to a zero value. These turn-on and turn-off transients may cause unacceptable spectral emissions.
Thus, there is a need for a pulse-shaping look-up table that reduces the turn-off and turn-on transients caused by traditional pulse-shaping look-up tables.